This application is based on and claims priority under 35 U.S.C. xc2xa7119 with respect to a Japanese Patent Application 2001-084511, filed on Mar. 23, 2001, the entire content of which is incorporated herein by reference.
The present invention relates to a water pump apparatus, and more particularly to a water pump apparatus which is used in a cooling system for vehicles.
A conventional water pump apparatus of this kind is disclosed in, for example, Japanese examined utility model publication No. 6(1994)-23760. As shown in FIG. 7, this water pump apparatus includes a body (a housing) 4 which is fixed to an engine block 3 via a gasket 2 and which has a central bore 5 and a pump chamber 6. A rotational shaft 8 having one end to which a pulley 7 is fixed is rotatably supported in the central bore 5 via a bearing 9. The pulley 7 is connected with a crank pulley (not shown) via a belt (not shown) and is rotated by the rotational force of a crank shaft (not shown). An impeller 10 is fixed to the other end of the rotational shaft 8 so that the impeller 10 is rotatably disposed in the pump chamber 6. The engine block 3 to which the body 4 is fluid-tight fixed is provided with a concave portion 11 which has an outer shape corresponding the pump chamber 6. The pump chamber 6 ensures a necessary volume in cooperation with the concave portion 11.
A mechanical seal 12 is disposed between the rotational shaft 8 and the body 4 for ensuring a liquid-tightness between the central bore 5 and the pump chamber 6. A water inlet 13 which is coaxially located at the rotational shaft 8 is provided with the engine block 3 and is opened into the concave portion 11. A water outlet 14 which is located at outer side of the impeller 10 in the radial direction is provided with the engine block 3 and is opened into the concave portion 11. Thus, when the rotational shaft 8 and the impeller 10 are rotated by the pulley 7, the water is sucked from the water inlet 13 to the pump chamber 6 and is discharged from the pump chamber 6 to the water outlet 14 by a centrifugal force.
The water which is leaked from the pump chamber 6 into the central bore 5 via the mechanical seal 12 flows into a drain pocket, namely a collection chamber portion 15 formed on the body 4 via a drain passage 16. The collection chamber portion 15 is opened in the opposite direction with respect to the engine block 3 and the opening of the collection chamber portion 15 is closed by a cap 17 which, is fixed to the body 4. A drain port 19 which is located in the upper side of the collection chamber portion 15 and which communicates between the collection chamber portion 15 and the atmosphere is formed on the body 4. Thus, when the collection chamber portion 15 is filled with the water leaked via the mechanical seal 12, the water is discharged from the collection chamber portion 15 via the drain port 19. In FIG. 7, a numeral 18 is a vapor outlet.
In the above mentioned prior water pump, since it is necessary to fix the cap 17 to the body 4 in a fluid-tight manner by, for example, press fitting and so on, the number of parts is increased and the precise processing is required for forming the opening of the collection chamber portion 15 and the cap 17. As a result, an increase in manufacturing cost cannot be avoided.
It is, therefore, an object of the present invention to provide an improved water pump apparatus which overcomes the above drawback.
In order to achieve this objective, according to the present invention, an improved water pump apparatus is provided which includes a body adapted so as to fix to a mounting surface of an engine and having a bore, a rotational shaft rotatably supported on the body via a bearing, an impeller fixed to the shaft and located in a pump chamber for forcibly supplying water from a water inlet to a water outlet, a seal member for sealing between the pump chamber and the bore of the body, and a collection chamber portion provided on at least one of the body or the engine so as to communicate with the bore between the bearing and the seal member via a drain passage and for collecting water leaked via the seal member, wherein the collection chamber portion is opened toward the mounting surface of the engine and an opening of the collection chamber portion is fluid-tightly closed by fixing the body to the engine.